Orbiting the nearest to Sol II, Terra IV is a planet never designed for complex land-dwelling life, but harboring it nonetheless. The extremely hot and arid inland climates and encompassing deep seas leave little room for the populations that have made home of short stretches of coast.
Colonies of H. sapiens originating on Terra I came to the planet ~12kya, primarily as explorers, prospectors and scientists. They sought to mine the planet of its resources, derive knowledge about its unique formation, and investigate it's rich but hidden underwater and microscopic life. These colonies were left without resources upon the collapse of Terra I. Those that had the capability and the fuel were able to make the journey to the nearby and more hospitable Terra III; the others were stranded. Many of the small populations were unable to survive, bringing H. sapiens nearly to extinction on the planet. The colonies that did survive eventually grew as they did on their home world, developing gradually from meager and distant agricultural settlements towards city-states and civilizations.